Would You Rebuild It?

[The Green GT]

Ive got a wrecked '94 GT that Im going to be pulling the engine and transmission from and Ill be transplanting it into a mid-90s Miata. The GT ive got has 116K on it, and it seems to run fine. I cant really drive it much because the wreck jacked up the passenger front wheel, but I can drive it to where I need it at my house.

I saw some oil coming from it. Looked like the rear main, but apart from that I didnt really see any leaks.

So would you completely tear it down and rebuild the bottom end? Im going to be putting A LOT of work into this project, so part of m wants to rebuild it and do it right, and part of me wants to save the money for other stuff. This is going to be a long project, I don't even have the Miata yet. Just doing it one piece at a time. Lol

When I had a '94 GT as my daily driver for like 6-7 years, I replaced or fixed pretty much everything on it. Gears, rebuilt transmission, head work, etc, so to be honest, the bottom end is pretty much the only thing I HAVENT worked on on these cars. That right there really makes me want to do it.

I have never rebuilt a bottom end of an engine, but I know I can do it. Just a matter or doing my research and making sure its all right. The fact that Ive never done pistons and stuff also makes me want to do it.

I plan on probably rebuilding it with stock replacement pistons, possibly a 347 stroker kit, but that's like an extra $500 right there.

My goals for the car are to be getting somewhere between 300-350HP after Ive had it up and running for a while. Probably wont go with a blower in the future, but who knows. The car will be track driven, but it will mainly be used as a fast street car to drive around town. So I don't want anything too crazy (yet).

Opinions?

 

[General karthief]

Rebuild it

 

[Davedacarpainter]

You're killing me here.

I really do like miata's, i've worked on a lot of them over the years. The idea of one with a 5.0 (or thereabouts) really makes my nerds tingle.

I'm going to,say this with my eyes averted and covered with my hand, "just do it, go on, just go ahead and do it".

BTW, screw a 347 and don't go any larger than a 331, my little 306 will make that power without a hick-up. Save yourself a rebuild in a few years.

I believe for a 347 you will need more than just a stroker though, @Boosted92LX am i right?

 

[General karthief]

What are you gonna do with the wreck?

 

[The Green GT]

You're killing me here.

I really do like miata's, i've worked on a lot of them over the years. The idea of one with a 5.0 (or thereabouts) really makes my nerds tingle.

I'm going to,say this with my eyes averted and covered with my hand, "just do it, go on, just go ahead and do it".

BTW, screw a 347 and don't go any larger than a 331, my little 306 will make that power without a hick-up. Save yourself a rebuild in a few years.

I believe for a 347 you will need more than just a stroker though, @Boosted92LX am i right?

Theyre not bad cars once you get over how they look. Lol. Just something about a car that light and nimble with a V8.

I know the stroker kit wouldn't give me more power, but it would give me the same power quicker. But the 5.0 already has low down tq.

What are you gonna do with the wreck?

Probably gonna pull whatever I can use/sell, and then sell it to a junkyard unless someone here wants it.

 

[Davedacarpainter]

Probably gonna pull whatever I can use/sell, and then sell it to a junkyard unless someone here wants it.

Oh good god, i'm already just one more fox body away from a divorce!

 

[TOOLOW91]

You're killing me here.

I really do like miata's, i've worked on a lot of them over the years. The idea of one with a 5.0 (or thereabouts) really makes my nerds tingle.

I'm going to,say this with my eyes averted and covered with my hand, "just do it, go on, just go ahead and do it".

BTW, screw a 347 and don't go any larger than a 331, my little 306 will make that power without a hick-up. Save yourself a rebuild in a few years.

I believe for a 347 you will need more than just a stroker though, @Boosted92LX am i right?

Plenty of stock block 347 stroker combos around..

 

[The Green GT]

Oh good god, i'm already just one more fox body away from a divorce!

Well this one is an SN95, so you're in the clear. Lol

 

[The Green GT]

Plenty of stock block 347 stroker combos around..

Are they worth it though? I know you get more tq, and an earlier power curve, but not sure how much.

 

[Davedacarpainter]

Plenty of stock block 347 stroker combos around..

Doesn't a stroker at that stage begin to have durability issues?

I suppose at that horsepower level, it wouldn't necessarily. But would a person stop at that level of hp with a 347?

Our am I just being a monkey repeating crap I've heard about an engine that I have no actual hands on experience with?

 

[General karthief]

Theyre not bad cars once you get over how they look. Lol. Just something about a car that light and nimble with a V8.

I know the stroker kit wouldn't give me more power, but it would give me the same power quicker. But the 5.0 already has low down tq.



Probably gonna pull whatever I can use/sell, and then sell it to a junkyard unless someone here wants it.

I would think there is a market for those, get'n kinda hard to find
What state you in? Never mind, Louisiana ain't that far, it wasen't floating was it?

 

[General karthief]

Doesn't a stroker at that stage begin to have durability issues?

I suppose at that horsepower level, it wouldn't necessarily. But would a person stop at that level of hp with a 347?

Our am I just being a monkey repeating crap I've heard about an engine that I have no actual hands on experience with?

I would think you could get a cam ground to make it idle like a stocker, maybe, someone help me here, I want some low down torque

 

[A5literMan]

Rebuilt bottom end vs stroker=depends....if you just want 300-350hp AND the bottom end parts are in good shape( i.e.You don't need a cyl bore,crank and rods check out) I would just rering,bearings,ARP rod bolts,new gaskets,seals,pump etc etc. With that done and you add a good h/c/i package, you'll have a motor capable of a reliable 300-350hp. Most important thing is to purchase good heads and a proper cam for making power.

If the block needs machine work and you end up needing new pistons go ahead and go with a cast crank stroker kit. I would use a scat kit. 331 or 347 will fine. There is a slight debate on the 347 piston ring style being a little less durable than a 331 but it is negligible imo. Having the extra stroke and a .030 overbore will add more power potential and torque over a 302. Torque is king in a street car. There is very little durability issues between a 306 vs a 331/347

 

[General karthief]

Oh, oh, F cam right?

 

[stpete]

I think you should seal the oil leaks and use the engine as is. LS and Honda swaps are the fashionable things for Miata because they are lighter and maintain the 50/50 weight distribution. They seem to have driven the 5.0 and SBC swap car prices down. I'd say keep it cheap.

 

[RangerJoe]

Adding a stroker kit without changing the induction will net you about 20 HP and a little more TQ, but that's it. If the bottom end is good in your current engine, the money spent on a stroker kit would be better spent on aluminum heads (AFR 165 or TFS 170) and a matching Intake and throttle body.

I did a 331 with my gt40 heads because I needed a complete over haul and the cost of stroker vs 306 was only a few hundred bucks. So I am speaking from experience here.

Joe

 

[MustangIIMatt]

Compression test, then a cooling system pressure test. If those two tell you the engine is healthy and there's no smoke or blow-by, install it. Ford 302s are fairly robust, I've dropped in a couple of yard-fresh 20-year old motors over the years without issues. Just fix the oil leak first.

 

[Boosted92LX]

I never ever drop a used engine in a car without popping the pan and inspecting the bearings. I've seen plenty of good running engines with bearings that needed to be replaced. Once you have copper showing, it's only a matter of time until it spins or ruins the crank or both... so it's silly to NOT check it for the price of an oil pan gasket. If the bearings look good, button it up, maybe change out the oil pump and water pump and rock on. If the bearings look tired, it may be time for a rebuild while the engine is out. I went through my son's 302 two years ago, checked the cylinders myself, honed them myself, bought a refurb .010-.010 crank kit (crank was wasted), re-ringed the stock pistons and went. It still runs just fine.

Like Joe mentioned, strokers are cool, but without attn to the top end the gains won't be huge. The stock heads, intakes and throttle bodies on these cars really are terrible. The aftermarket cylinder heads flow about (or less than)what stock chevy LS heads do, as @tannerc91gt can tell you.. so from a performance standpoint, spend your money on the top end for power. If you can afford both, or plan on upgrading heads soon, then opt for the stroker kit.

 

[tannerc91gt]

Get away with as little machine work as possible IMO. Strokers are cool, and especially great if you wanna brag about it at a car show but you can accomplish what you're after on stock cubes with the right attention to cylinder heads and valvetrain. More bang for your buck IMO.

I will second the notion that stock ford cylinder heads are junk. A lot of ground to be gained there.

 

[Chuckman]

The only reliability issue between a modern 347 and 331 is a 347 is more likely to exceed the power limitations of a stock block.